Apologies if its addressed elsewhere.....
I get the massive pile up of pirates during the game as well....but not too big a deal on my gamespeed. I do notice that having pirates enabled in single player makes the game unbalanced....for me. There seems to be way too many pirates in a raid and most often its enough to weaken to insignificance another faction. ie wiping out whole systems frequently. Early on I seem to never get much of bounty put on me and they attack elsewhere.
Along that line....is there something up with diplomacy? Even when I research it up early, the benefits of completing a task are still limited and I am most often past midpoint of the game by the time I can even form a trade pact.